1. Field of the Invention
The present invention relates to an apparatus for manufacturing golf balls and more particularly to an apparatus for removing a burr from a seam of a golf ball with a high accuracy and speed, so that the golf ball has no great circle path which does not necessarily intersect with dimples on the surface thereof.
2. Description of the Related Arts
Generally, resin is shaped into a golf ball by a pair of semispherical molds 1A and 1B as shown in FIG. 12.
That is, a concave surface 3 having dimple-forming projections 2 is formed on each of the molds 1A and 1B. When connecting portions 4 of the molds 1A and 1B are superimposed on each other, the concave surfaces 3 collectively form a cavity. The golf ball is shaped by pressure molding or injection molding of resin into the cavity.
As shown in FIG. 13, in a golf ball 5 formed by using the molds 1A and 1B, a burr 6 is formed on a portion corresponding to the connecting portion 4 of the molds 1A and 1B, namely, a seam 5a.
The burr 6 on the seam 5a is cut off the seam 5a in a subsequent process. But if dimples 8 are formed on the seam 5a, i.e., if the seam 5a is irregular, the burr 6 cannot be cut off the seam 5a. Thus, the dimples 8 cannot be formed on the seam 5a. Hence, dimple-forming projections 2 are not arranged in the vicinity of the connecting portion 4. Accordingly, with the removal of the burr 6 from the golf ball 5 manufactured by using the molds 1A and 1B, a great circle path 9 is formed on the seam 5a as shown in FIG. 14 that does not intersect with dimples 8.
The great circle path 9 badly influences the flight performance of its golf ball and the aerodynamic symmetrical qualities. Therefore, methods for manufacturing the golf ball having no great circle path have been proposed as described below.
In a method as disclosed in Examined Japanese Patent Publication No. 3-81394, convexes 12 and concaves 13 are alternately formed on the connecting portion 11 of molds 10A and 10B as shown in FIG. 15. A seam 14a formed on a golf ball 14 is zigzagged to correspond to the zigzagged configuration of the connecting portion 11 of molds 10A and 10B. In this manner, the great circle path is not formed on the surface of the golf ball 14.
In another method for manufacturing a golf ball having no great circle path thereon, dimples are not formed in the resin-molding process, but by a cutting process to be performed after the resin-molding process. This method is disclosed in Japanese Laid-Open Patent Publication No. 64-8983.
The above-described conventional methods are, however, inappropriate for mass-production of golf balls and incapable of manufacturing them with high accuracy. In fact, golf balls having a great circle path with intersecting dimples are unavailable on the market.
In the method disclosed in Examined Japanese Patent Publication No. 3-81394, it is necessary to shape the connecting portion 11 of the molds 10A and 10B into a complicated configuration. Therefore, it takes considerable time to form the molds 10A and 10B into the above-described configuration, which increases manufacturing costs. In addition, the formation of the molds 10A and 10B leads to variations in size and configuration. Accordingly, it is difficult to shape resin into golf balls having a uniform dimension and configuration using the molds 10A and 10B.
Normally, 280 to 540 dimples are formed on the surface of the golf ball. In the method disclosed in Japanese Laid-Open Patent Publication No. 64-8983, dimples are machined one by one. Therefore, the substantial time and labor required by this method makes it inappropriate for mass-production. In addition, the dimples vary in dimension and configuration.